BARRON RIVER DELTA INVESTIGATION

D.A. Robinson, D.J. Cook, J.G. Barff

Abstract


The Barron River flows to sea through a 50 km2 alluvial Delta on the narrow coastal plain near Cairns, Queensland in north eastern Australia. The Delta is in the tropics at 17 degrees south latitude. Most of the 2175 km2 catchment lies above 450 m above sea level. The coastal portion of the catchment has an average annual rainfall in excess of 2000 mm. River flows are highly variable with peak flood flows of over 4000 m3s"', and dry season flows of less than 15 m3s"'. The Delta is tidal with ocean tides having a range of 1.8 m at Spring Tides. There are three water storages on the catchment, one on the upper catchment having an ungated spillway and a capacity of 407 x 106 m3 for irrigation purposes and the other two just upstream of the Delta, are a small weir of 1.7 x 106 m3 capacity to regulate water supply to the Barron Gorge Hydro-electric Power Station, and Copperlode Falls Dam on Freshwater Creek, a 45 x 106 m3 ungated storage to provide water to Cairns City and the nearby Mulgrave Shire. The Delta consists of alluvial soils which support 3600 hectares of sugar cane farm land. The beaches in the Delta are being developed as resort towns and dormitory suburbs. Sand and gravel is reularly dredged from the lower reaches of the main river in the Delta at the rate of 50,000-80,000 m3 per year. Increasing scarcity of sand sources, and the concern that dredging and dam construction is threatening beach sand sources have raised conflicting pressures on the Authority which licences the extraction of sand and gravel from the river. This, coupled with regular flooding of the Delta and the cutting of major highways, and the continuing erosion of cane farm land has initiated a major data collection programme as a prerequisite to formulating solutions for the flooding and erosion problems.

Keywords


river delta; Barron River; river investigation

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